<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">

<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title>累加按钮，自加1</title>
    <style>
    body {
        text-align: center;
    }
    
    input {
        font: 12px arial;
        cursor: pointer;
        padding: 0 10px;
    }
    </style>
    <script type="text/javascript">
    window.onload = function() {
        var aBtn = document.getElementsByTagName("input")[0];
        var i = 0;

        aBtn.onclick = function() {
            aBtn.value = ++i;
            alert(i)
        }
    }
    </script>
</head>

<body>
    <input type="button" value="0" />
</body>

</html>
